Impact of nonuniform heated plate on double-diffusive natural convection of micropolar fluid in a square cavity with Soret and Dufour effects

A numerical work has been carried out to study the effect of heated plate on double diffusive natural convection in a cavity with the presence of Soret and Dufour effects. The vertical left and right sidewalls of the cavity are maintained at constant cold temperatures while the lower and upper walls are considered insulated. The influence of pertinent parameters such as Rayleigh number, Schmidt number, vortex viscosity parameter, Soret and Dufour coefficients and plate non-uniformity parameter on the flow and heat transfer characteristics has been examined. Numerical results show that the heat and mass transfer rate increases with the rise of the Rayleigh number and Schmidt number. It is found that the heat and mass transfer rate are considerably suppressed by the vortex viscosity parameter. In addition, it is observed that the average Nusselt number increases and Sherwood number decreases with increasing Soret and Dufour effects.     

Studies of dynamic crack propagation and crack branching with peridynamics

In this paper we discuss the peridynamic analysis of dynamic crack branching in brittle materials and show results of convergence studies under uniform grid refinement (m-convergence) and under decreasing the peridynamic horizon (δ-convergence). Comparisons with experimentally obtained values are made for the crack-tip propagation speed with three different peridynamic horizons. We also analyze the influence of the particular shape of the micro-modulus function and of different materials (Duran 50 glass and soda-lime glass) on the crack propagation behavior. We show that the peridynamic solution for this problem captures all the main features, observed experimentally, of dynamic crack propagation and branching, as well as it obtains crack propagation speeds that compare well, qualitatively and quantitatively, with experimental results published in the literature. The branching patterns also correlate remarkably well with tests published in the literature that show several branching levels at higher stress levels reached when the initial notch starts propagating. We notice the strong influence reflecting stress waves from the boundaries have on the shape and structure of the crack paths in dynamic fracture. All these computational solutions are obtained by using the minimum amount of input information: density, elastic stiffness, and constant fracture energy. No special criteria for crack propagation, crack curving, or crack branching are used: dynamic crack propagation is obtained here as part of the solution. We conclude that peridynamics is a reliable formulation for modeling dynamic crack propagation.     

Catalytic solid-phase seeding of silicon nanowires by nickel nanocrystals in organic solvents

Colloidal nickel (Ni) nanocrystals were used to direct the synthesis of crystalline silicon (Si) nanowires in an organic solvent. The reaction temperatures ranged from 400 degrees C to 520 degrees C with pressures from 14.3 to 23.4 MPa, conditions that are well above the critical point of the solvent. The Ni nanocrystals play two roles in the synthesis: (1) Ni catalyzes the decomposition of the silicon precursors, i.e., arylsilanes, alkylsilanes, and trisilane, to silicon; (2) Ni nanocrystals induce silicon crystallization through the solid-phase alloying of Si in the Ni seeds. We call this nanowire growth mechanism supercritical fluid-solid-solid (SFSS) synthesis.     

Nanosurface-confined anisotropic growth and magnetism of ellipsoidal alpha-Fe nanogranules

We have investigated the nanosurface-confined anisotropic growth of ordered-ellipsoidal Fe nanogranules when an Fe plume was deposited at a slanting angle onto an anodized aluminum oxide (AAO) film. Layer-by-layer growth was also investigated. This growth is driven by two critical factors: (1) a new rhombic AAO cell and (2) the slanting deposition of the Fe plume. During slanting deposition, the rhombic AAO cell induces strong restrictions in the nucleation site, growth direction, and granular size; therefore, the degree of freedom during growth is restricted. The magnetic dipoles of the ordered Fe nanogranules are placed along the long axis of the ellipsoid at an angle of 180 degrees (antiparallel) due to the demagnetizing field, shape anisotropy, and magnetic dipole-to-dipole interactions.     

Consolidation and mechanical properties of nanostructured MoSi2-SiC-Si3N4 from mechanically activated powder by high frequency induction heated sintering

A dense nanostructured MoSi₂-SiC-Si₃N₄ composite was sintered by the high frequency induction heating method within 2 min from mechanically activated powder of Mo₂N, Mo₂C and Si. Highly dense MoSi₂-SiC-Si₃N₄ composite was produced under simultaneous application of a 80 MPa pressure and the induced current. Mechanical properties and grain size of the composite were investigated. The average hardness and fracture toughness values obtained were 1420 kg/mm² and 4.5 MPa m^1/2, respectively.     

Carbon contamination analysis and its effect on extreme ultra violet mask imaging performance using coherent scattering microscopy/in-situ accelerated contamination system

The coherent scattering microscopy/in-situ accelerated contamination system (CSM/ICS) is a developmental metrology tool designed to analyze the impact of carbon contamination on the imaging performance. It was installed at 11B EUVL beam-line of the Pohang Accelerator Laboratory (PAL). Monochromatized 13.5 nm wavelength beam with Mo/Si multilayer mirrors and zirconium filters was used. The CSM/ICS is composed of the CSM for measuring imaging properties and the ICS for implementing acceleration of carbon contamination. The CSM has been proposed as an actinic inspection technique that records the coherent diffraction pattern from the EUV mask and reconstructs its aerial image using a phase retrieval algorithm. To improve the CSM measurement accuracy, optical and electrical noises of main chamber were minimized. The background noise level measured by CCD camera was approximately 8.5 counts (3 sigma) when the EUV beam was off. Actinic CD measurement repeatability was <1 A (3 sigma) at 17.5 nm line and space pattern. The influence of carbon contamination on the imaging properties can be analyzed by transferring EUV mask to CSM imaging center position after executing carbon contamination without a fine alignment system. We also installed photodiode and ellipsometry for in-situ reflectivity and thickness measurement. This paper describes optical design and system performance observed during the first phase of integration, including CSM imaging performance and carbon contamination analysis results.     

T-Cell-Mimicking Nanoparticles for Cancer Immunotherapy

Cancer immunotherapies, including adoptive T cell transfer and immune checkpoint blockades, have recently shown considerable success in cancer treatment. Nevertheless, transferred T cells often become exhausted because of the immunosuppressive tumor microenvironment. Immune checkpoint blockades, in contrast, can reinvigorate the exhausted T cells; however, the therapeutic efficacy is modest in 70–80% of patients. To address some of the challenges faced by the current cancer treatments, here T-cell-membrane-coated nanoparticles (TCMNPs) are developed for cancer immunotherapy. Similar to cytotoxic T cells, TCMNPs can be targeted at tumors via T-cell-membrane-originated proteins and kill cancer cells by releasing anticancer molecules and inducing Fas-ligand-mediated apoptosis. Unlike cytotoxic T cells, TCMNPs are resistant to immunosuppressive molecules (e.g., transforming growth factor-β1 (TGF-β1)) and programmed death-ligand 1 (PD-L1) of cancer cells by scavenging TGF-β1 and PD-L1. Indeed, TCMNPs exhibit higher therapeutic efficacy than an immune checkpoint blockade in melanoma treatment. Furthermore, the anti-tumoral actions of TCMNPs are also demonstrated in the treatment of lung cancer in an antigen-nonspecific manner. Taken together, TCMNPs have a potential to improve the current cancer immunotherapy.